Analysis and improved operation of a PEBB-based voltage-source converter for FACTS applications

The demand of power-electronic devices is increasing in several applications, and power-electronic building blocks (PEBBs) are a strategic concept to increase the reliability of the power-electronic converters and to minimize their cost. A possible solution to increase the power rate of these converters is the use of series or parallel connected PEBBs in multipulse configurations. Magnetic elements, such as zig-zag transformers, phase-shifted transformers (pst), or zero-sequence blocking transformers (ZSBT), are used to interconnect the PEBBs. In this paper, the operation of multipulse converters will be analyzed, describing the harmonic cancellation and minimization techniques that could be used in these multipulse converters, focusing on the power-electronics flexible ac transmission systems devices installed at the NYPA Marcy substation. In order to improve the dynamic response of this system, the use of selective harmonic elimination modulation is proposed and implemented.